Fan service with some nice art?

There is a reason Pokeshipping is so popular, and it's not just because of genwunners. Side note: did you ever notice that most media that is not Pokémon, or associated heavily with it, uses art from generation 1? That's because gen 1 is the least hated generation. No matter which generation is your favorite, it's hard to hate the original, since if that wasn't liked, there would never be sequels. But back to the main point. Pokeshipping is popular because it was intended. During the writing of the original series, Game Freak wasn't out with a sequel yet, and was riding on the success on Red, Green, Blue, and Yellow. Also, most anime is only prepared to go for one season, and Pokémon was no different, ending with the first movie and the introduction of Mew. You may know already about the unused ending of the first movie, where an older Misty and her child, talking about the great Pokémon trainer that is that child's father. There are also very obvious moments of Misty's jealousy, though some may not be canon since the 4kids dub added some things that weren't in the Japanese dub. There is still enough that 4kids couldn't have tampered with to conclude something at least on Misty's side. I'm going to name a few examples, but not all. If you want a full list, go to bulbapedia or the comments, surely someone will add more down there.

After Misty gets her bike back, she refuses to stop traveling with Ash specifically, though it can be interpreted differently.

In America, it's not uncommon for kids to show intense feeling by bullying, since their brains haven't developed enough to fully understand the meaning of some emotions. Misty picks on Ash A LOT, and remember, they are both children.

My favorite, and maybe the most obvious: every time Misty gets angry when another girl has a moment with Ash. I personally liked when Melody kissed him during the Lugia movie.

In conclusion, Pokeshipping was supposed to be canon, but couldn't be because Ash had to continue his journey.